Mercury-arc lamp



P. G. NUTTING.

MERCURY ARC LAMP.

APPLICATION man MAR.13.1915.

L32,0@Y0 l Pafented Oct. 28,1919.

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WITNESSES: INVENTOR Y f I a ATT RNEY

UNITED STATES PATENT oFFIcE,

PERLEY G. NUTTING, oF WILKINSBURC, PENNSYLVANIA, AssIGNoR To WEST- INcHoUsE ELECTRIC s MANUFACTURING COMPANY, A CORPORATION oF PENNSYLVANIA.

MERCURY-ARC LAMP.

Specication of Letters Patent.

Patented (het. 28, 1919.

Application led March 13, 1918. Serial No. 222,053.

To all whom z't may concer-n Be it known that I, PEnnEY G. NUTTING, a citizen 0f the United States, and a resident of WVilkinsburg, in the county of Allegheny and IState of Pennsylvania, have invented a new and useful Improvement in Mercury-Arc Lamps, of which the following is a specification.

My invention relates to new and useful improvements in mercury-arc lamps and more particularly lamps of this character lintended for laboratory purposes, and it has for its primary object, the provision of a mercury-arc lamp of increased efficiency because of structural features which increase the intensity of thel light, prolong the life of the lamp and render its operation, without danger of injury to the eyes convenient.v

To the best of my knowledge, laboratory arc lamps heretofore employed have either been provided with bodies of fused quartz, rendering their use dangerous to the eyesight, or of glass of such a character as to require the use of water baths to keep them cool, by preventing formation of highdensity vapors which would put out the arcs, the water-cooling rendering their employment inconvenient.

I have found that these diiculties may be overcome byproviding means for air cooling and by forming the body of the lamp of hard glass and the leading-in wires and terminals of heavy tungsten wire. I have also found a simple and effective means for increasing the intensity of the light pro vided by the lamp.

In the drawing, the single ligure of which is an elevation ofv a mercury-arc lamp constructed in accordance with my invention, is shown a tubular lamp body of substantially inverted U-shape, Including an intermediate arc tube 10, a depending anode leg 11 and ya depending cathode leg 12, each of said ylegs being sealed at its lower end, l

The cathode leg 12, intermediate its ends,

has its internal diameter reduced to provide a constricted passage 16, for a purpose which will be hereinafter specified. The

lo'wer end of the'cathode legr 41Q is provided with a bulb-shaped enlargement 17 partlally filled with mercury, while the anode leg 11 is substantially filled with mercury.

An air-cooling bulb 18 of suitable size couununlcates, through a relatively large opening 19, with the intermediate portion of the arc tube l0. This entire body, including the arc tube, cathode and anode legs and air-cooling bulb 18, is formed of hard glass that softens only at a high temperature.

I have found, from actual practice, that a mercury-arc lamp formed of such glass and provided with tungsten terminals, will remaln clean longer and give longer life than lamps made of soft glass and provided with platinum leading-in wires. In addition to this, the air-cooling bulb, if of the proper size and proportions, serves to control the vapor pressure in the arc tube fully as well as a water bath and is, of course, much more convenient. Lamps of this type have been operated continuously for fifty hours without any sign of deterioration, a performance not approached by annother'lamps of this class of which I have owledge. p

The restricted passage 16 should be sufficiently large to allow mercury to drop readily through it and yet small enough to condense the vapor that passes through it. A passage of approximately three millimeters in diameter has been employed with success, and the brilliancy and intensity of the light provided by the lamp has been thereby materially increased.

It will, therefore, be clear that I have provided an improved form of mercury-arc lamp by providing an air-cooling structure, lby the employment of hard glass, by using tungsten leadin wires and terminals and by constricting the passage of the cathode leg, to increase the light intensity.

Although I have illustrated and described the various features of my improved lamp in considerable detail, it will be appreciated that no limitations, other than those set forth in the claims, are to be imposed upon my invention.

I claim as my invention:

1'. A mercury-arc lamp including anode and cathode legs and a connecting arc tube all formed of hard glass that softens onl at a high temperature, and tungsten leads-7 ing-in Wires and terminals sealed into the ends of the legs.

2. A mercury-mc lamp including anode und cathode legs und a connecting are tube all of hzu'd glass that softens only at a, high temperature, tungsten lead-in Wires and terminals sealed into the ends of the legs, und :tir-cooling means associated with the :u'c tube.

3. A mercury arc lamp including anode und cathode legs, a connecting are tube, and an air-cooled |bulb having unrestricted oommunication with the are tube, all of such pau-ts being formed of hard glass that softens only at a high temperature and the intern'nedizrte portion of the cathode leg having a constricted passage, and tungsten leading-in Wires and terminals fused into the ends of the legs.

In testimony whereof, I have hereunto slbscribed my name this 28th day of Feb. 1 18.

PERLEY Gr. NUTIINlGr= 

